In general, a handoff may occur when a communications device, also commonly referred to as a mobile station, user equipment, terminal, user, and so on, moves out of a coverage area of a first access point, also commonly referred to as a base station, base terminal station, controller, NodeB, enhanced NodeB, and so forth, and into a second access point. When a handoff occurs, control of the communications device's communications changes hands from the first access point to the second access point. There may be a certain level of signaling that occurs in order to setup and perform the handoff.
FIG. 1 illustrates signaling occurring in a prior art handoff for a communications device operating in a code division multiple access (CDMA) 1× Interoperability Specification (IOS) based femto cell communications system 100. As shown in FIG. 1, the signaling is for an inter-femto access point (FAP) handoff, but with both FAPs being connected to a single femto gateway (FGW). In CDMA 1×IOS communications system 100, a mobile station (MS) 105, another name for the communications device, may be communicating through a first FAP 110.
Communications to and from MS 105 may flow through first FAP 110 over a CDMA 1× air interface. First FAP 110 may provide an A1p interface to FGW 120, and FGW 120 may provide an A1p interface to a mobile switching center (MSC)/CDMA softswitch center (MSCe) 125. First FAP 110 may also provide an A2p interface to a media gateway (MGW) 130. A femto security gateway 120, positioned between first FAP 110 and FGW 120 may provide a secure Internet Protocol (IP) tunnel(s) between first FAP 110 and FGW 120 over an unsecured IP transport network used in CDMA 1×IOS communications system 100.
In a macro network comprising a macro base station controller (BSC) 135 and a macro cell 140, when MS 105 crosses a BSC boundary, an inter-BSC handoff occurs and MS 105 reports the signal strength(s) of target cell(s) of the target cells list to a source BSC. The source BSC may then initiate a handoff procedure. A target BSC accepts the handoff and transfers hard handoff parameters to the source BSC via MSC/MSCe 125. The source BSC may dictate MS 105 perform a handoff to the target BSC. When MS 105 appears at the target BSC, the handoff procedure completes.
During an inter-BSC handoff procedure, MSC/MSCe 125 may mainly transfer handoff related information between the source BSC and the target BSC. If a user plane A2p bearer related parameter is changed, MSC/MSCe 125 may maintain the latest A2p bearer related parameter for user plane traffic. MSC/MSCe 125 may also maintain latest cell information of MS 105 for mobility management purposes.
Whenever a MS moves between FAPs connected to the same FGW (such as when MS 105 moves (movement shown as dashed dotted line) into a coverage area of FAP 112, an inter-FAP handoff procedure is initiated. Considering that there may be hundreds or thousands of FAPs connected to a single FGW, a very large number of inter-FAP handoff procedures may be initiated, potentially leading in a huge number of signaling messages coming through MSC/MSCe 125 from FGW 120. MSC/MSCe 125 is required to handle the high number of signaling messages for the MSs, thereby impacting the performance of macro cell users of MSC/MSCe 125.
Therefore, there is a need to reduce the impact of signaling required for femto cell mobility on MSC/MSCe 125 and to reduce bandwidth requirements between FGW 120 and MSC/MSCe 125.